There is at least one episode with what I consider an unfinished storyline. In its own right it’s telling 'a' story of the crew’s battle to save the ship and a life form that is 'somehow' growing in the cargo bay, yeh yeh, the crew are always saving new life forms et al.
(TNG) S7E23 - Emergence - The story builds to a climax when the new life form emerges from the Enterprise and floats off, leaving the viewer wondering what the hell that was all about and where it’s off to? Is it going to start a planet of multicolour tube babies? Is it going to get broken up by a crowd at a rave and banded about as glow sticks? Will it encounter the Klingons who go on the eat it?
The life form is suggested to be the sum of the crew’s experiences /library of stories (shudders) but it leaves the viewer hanging by this awful thread never offering any kind of closure imho.
I need the satisfaction of that ‘ah ha’ moment…
Can anyone offer me closure?